EP 1 364 695 A1 discloses an air filter that is integrated into the intake manifold of an internal combustion engine in order to subject the combustion air to be supplied to the cylinders of the internal combustion engine to a filtration action. The air filter is substantially of a three-part configuration and comprises a filter element in a filter housing that is configured as an exchangeable filter cartridge through which the combustion air flows axially and that is insertable radially by means of a closable lid into the filter housing. The filter cartridge has arranged upstream thereof a cyclone preseparator that serves for separation of coarse dirt particles. Downstream of the filter cartridge there is a secondary or fine filter element that also is insertable radially into the filter housing when the lid is open. The cyclone preseparator, the filter cartridge, and the fine filter element are positioned axially sequentially behind one another and the combustion air to be filtered passes through them without deflection in the axial direction.
As a main filter element that is received in the filter cartridge, for example, wound filters are suitable that are comprised of a corrugated filter material that is wound about a core, wherein as a result of the corrugation axial flow passages are formed by the filter element that are closed of alternatingly at the end faces. Such a filter element is, for example, disclosed in U.S. Pat. No. 7,008,467 B2.
Also known are filter elements that are comprised of a star-shaped folded filter element in the form of a filter bellows whose filter folds extend in radial direction wherein the front edges of the filter folds extend in axial direction.
EP 1 494 785 B1 discloses an air filtering device and a method for its installation. An air filter with a first stage and with a prefilter with multiple centrifugal separators with a dust separating tube and a second stage with an air filter cartridge is arranged downstream of the tubular filter. The air filter cartridge comprises a Z filter medium, a sealing element extending completely about the circumference of the Z filter medium construction and having an intake flow surface and an exit flow surface. The Z filter medium comprises several intake fold passages that are open at the intake flow surface and are closed off for passage of air at the exit flow surface. Several exit fold passages are provided that are closed at the intake flow surface and are open at the exit flow surface for outflow.
The air filter comprises a housing with at least a first and a second part wherein the sealing element comprises a first side and an opposite second side as well as an outer annular surface.
The sealing element is moreover arranged between the first part and the second part of the housing in order to provide an axial sealing action.
Each of the centrifugal separators has a sidewall, an interior, and baffles. Moreover, a safety element is installed operatively in the housing behind the primary filter element at the outflow side.
The safety element comprises a frame with an outer surrounding skirt, a packing set arranged at the surrounding skirt, and a folded filter medium area arranged within the frame as well as a grip.
The packing set moreover forms a seal within the housing.